Surgical Component Molding

Process problem solving meets parts demand

Trocars are complex tools that provide surgeons with a minimally invasive tunnel for insertion of instruments such as laparoscopes for visual examination, specimen removal and other procedures. The thin-walled trocar sleeve relies on a series of external, circumferential barbs for stability during a procedure. Classic Industries Inc, Latrobe, PA, uses polycarbonate from Dow Chemical Company, Midland, MI, in a multi-cavity mold to produce the hollow sleeves, which are approximately 5-in. long with varying diameters and 0.020- to 0.030-in. wall thicknesses.

“Just two years ago, before Classic had the molds, market demands were not being met and our customer (a Fortune 100 medical device manufacturer) was in a backorder situation,” states Spencer Siegel, vice president of market development for Classic. “We reworked the molds, employed the latest injection molding technology, and automated the injection molding and pad printing processes. The re-engineered process significantly increases the rate of production, and now our customer is in an inventory situation.”

“Automating the pad printing line not only reduced cost, but also increased consistency and reduced scrap,” related Bill Larrimer, Classic’s vice president of engineering. “The printing line now prints and inspects all parts before sending them for packaging. This resulted in a 75% reduction in scrap due to printing.”

“We looked at the project with our customer to determine not only their immediate goals, but what was anticipated in the future,” Siegel adds. “Our customer also wanted to increase their internal assembly line performance and reduce total part costs.”

Classic’s team examined the mold and the resin selection, and conducted mold flow analysis of the part. Larrimer says that “an obstacle we had to overcome was how to mold polycarbonate in a multi-cavity mold to make a part with a wall thickness of 30 thousandths of an inch over five inches without flash. And, do it consistently. The solution was to rework the existing molds, and use a high-pressure, high-speed Netstal Synergy machines and Fanuc Roboshot electric machines with high performance packages; both are excellent for repeatability and speed. With these machines, the injection time to fill a sleeve is faster than a snap of your fingers (less than a tenth of a second), and the process is consistent and stable.” In the end, Classic was able to achieve their customer’s objectives to increase the level of production of quality parts at a competitive price using their existing molds. With a consistent supply of parts, further cost improvement was realized through improved efficiency of the manufacturer’s internal assembly line performance.

“The trocar sleeve is typical of the projects we receive. I think the first reason we succeed is that our team really enjoys a challenge. Naturally, this is backed up by our many years of collective experience, and state-of-the-art equipment. This all came together to bring this customer from a backorder position to one where inventory keeps pace with demand,” says Larrimer. He adds, “We continually look for ways to increase performance and reduce total manufacturing costs for all our customers. In fact, with this part we’re re-thinking the current manufacturing and assembly techniques. We’re considering replacing some post-molding operations with molded-in features to make the design even more robust. If you do not design the tooling and automation for manufacturing, you have done nothing to help your customer’s bottom line; you have created only an R&D project.”

Nearly seven million surgical trocar sleeves a year continue to be produced smoothly by Classic after two years of 24/7 production. Through process improvements and innovative engineering, Classic obtained a two-fold increase in production, improved quality, reduced costs and eliminated the need for the customer to invest in additional molds.

—SG

Custom Complex Flow Valve

New solenoid 3-way valve meets flexibility demands

A manufacturer of precision dispensing syringe systems needed a special valve that could be assembled on top of multiple syringes, and mounted side-by-side while functioning in traditional aspirate and dispense modes, as well as a wash cycle. Speed and flexibility were also necessary to accommodate changing requirements and fast needle cleaning.

When standard valves were not able to perform as desired, the manufacturer contacted Bio-Chem Valve, Inc, Boonton, NJ, to develop a custom modified version of an existing valve product. The traditional round valve bodies with ports positioned at 90-degrees did not allow efficient side-by-side mounting, and the standard 3-way valve configurations with one normally-closed, one normally-open and one common port, were not able to handle the wash cycle requirement in which the normally-open and normally-closed ports both need to be open at the same time.

Engineers developed a small footprint valve solution that handles the multiple tasks. The resultant dual-solenoid 3-way valve features a rectangular body design that is capable of switching on demand to allow independent operation of each inlet port. The four possible on/off combinations between the normally-open and normally-closed ports (both on, both off, on/off, off/on) meet the wash cycle requirement. In addition to providing a compact component that offers the flexibility and speed to select desired pathway combinations for efficient, low-cost flow switching, the new valve also saves on power usage, circuitry and number of controls.

—SG